He played his own cards on the ban. You don't walk into the ring after someone wins a belt, the only time you did this is when the promoter wants you to. The UFC does this quite a bit, with the most recent one being Rashad going in when JBJ won. Rashad said he didn't want to enter initially but the UFC put him in that situation.
The Cesar Gracie possie/team is too large to begin with, the ring was practically crowded, whereas the UFC only allows your cornermen to enter and not your whole training team.
I don't necessarily agree on the ban but he deserved some type of punishment for just barging in there, and it shouldn't have even been done by CBS. They are the ones who should be happy about it, if anything, Miller would attract bigger TV numbers on his next fight.